Practical Conduct of Anesthesia

Pre-anaesthetic assessment: very important

If not performed by the anaesthetist it is considered as negligence

All data must be written in the preoperative note.

Establishment of Rapport

History

• Current medical problems - medical/surgical
• Medication history: present and past medication including steroids
• Drug intolerances
• Allergies including Latex
• Social history: Drug abuse e.g Heroin, Alcohol, Tobacco.
• Anaesthetic history: previous anaesthetics problems and family history of complications with anaesthetic e.g malignant hyperthermia
• Review of organ systems

Physical examination

• Vital signs - BP, Pulse, and Respiratory Rate
• Airway: Physical signs such as prominent incisors, large tongue, limited movement of TM-joint or cervical spine, and Mallampati grade may suggest difficult intubation.
• Patients should be inspected for loose, chipped teeth and the presence of gaps, bridges, or dentures.
• Examination of CVS and RESPIRATORY system should be carried out using standard inspection, palpation, percussion, and auscultation.
• Neurological examination is desirable when regional anaesthesia is contemplated.

Investigation

• Full blood count
• Coagulation screen on patients on anticoagulant/Aspirin and those with a bleeding tendency.
• Fasting blood sugar on diabetic patients
• Electrolytes/urea/creatinine
• Urine analysis
• Chest X-ray is routine in patients with severe respiratory or cardiac problems.
• ECG is routine in all patients suffering from hypertension and heart disease. It is also routine in healthy patients over 50 years of age.
• Sickling test
• Genotype if sickling Test is positive
• Pregnancy test in suspected cases of early pregnancy.
• Routine testing for HIV is still controversial

ASA Physical Status

Mallam Patti

Consent

Fasting Guidelines

Premedication

Conduct of Anaesthesia is generally broadly divided into:

1. Induction
2. Maintenance
3. Recovery

INDUCTION

Before administering anesthesia, check the anesthesia machine and other equipment, e.g., laryngoscope.

For general anesthesia, induction can be done by inhalational, IV, IM, or rectal (stealth induction).

INHALATIONAL

Administered through a facemask, usually indicated in:

• A. Children
• B. Upper or lower airway obstruction
• C. Cases where IV induction is very risky (e.g., difficult intubation)

The procedure should be well explained to the patient beforehand.

Select the gas mixture.

Problems:

1. Slow induction
2. Salivation
3. Laryngospasm, hiccups
4. Wastage of anesthetic vapors
5. Pollution

GUEDEL'S CLASSIC SIGNS OF ANESTHESIA

Stage 1: Analgesia

It is the period from the beginning of anesthesia until the loss of consciousness. Respiration is irregular and small in volume. Pupils are small, and reflexes are mostly intact.

Stage 2: Excitement

The period from the loss of consciousness to the starting of rhythmic respiration. Respiration is large in volume and irregular. Eyelash reflexes are absent, while other reflexes are intact. The patient is struggling and restless.

Stage 3: Surgical Anesthesia

The period extends from the onset of regular rhythmic respiration up to respiratory paralysis. It has 4 planes:

• Plane 1: Starts from the onset of regular respiration and ends when the eyeball comes to rest in the central position.
• Plane 2: Starts from the cessation of eyeball movement and ends when intercostal muscle paralysis starts.
• Plane 3: Progressive intercostal paralysis until its completion. Only diaphragmatic respiration continues.
• Plane 4: Respiration ceases.

Stage 4: Medullary Paralysis

Characterized by apnea, intense muscular relaxation, and dilated fixed pupils. This stage is associated with excessive anesthesia, and the patient is in a critical condition.

INTRAVENOUS INDUCTION

• IV induction agents are used
• It is the most pleasant, can cause rapid induction
• Can be used for emergency surgery
• Drugs to be given must be selected carefully
• Common drugs are; thiopentone, ketamine, propofol

Complications

• Regurgitation, vomiting, aspiration pneumonitis
• Intra-arterial injection of thiopentone
• Cardiovascular depression
• Respiratory depression
• Histamine release
• Porphyria
• Muscular movements
• Drug reaction

MAINTENANCE OF ANAESTHESIA

1. Inhalational agents
2. IV anaesthetic agents
3. IV opioid
4. The above agents can be used alone or in combination
5. Maintain neuromuscular block by a long-acting agent
6. Adequate analgesia e.g., opioids + NSAIDs + PCM, can also use regional tech.

After surgery recovery from anesthesia should be smooth if GA is used and adequate post-op monitoring should be ensured. Adequate post-op analgesia as well.

Most importantly proper documentation of the anesthesia chart must be kept.

Anesthetic gases and vapors are administered through a tube inserted into the trachea through the nose or mouth or transtracheal route.

OBJECTIVES:

1. To ensure ventilation/oxygenation
2. To ensure airway patency
3. To protect against pulmonary aspiration
4. To provide separate ventilation to each lung
5. To protect the airway from contamination
6. To facilitate tracheobronchial toilet

INDICATIONS

1. Head/neck surgery, major surgery, abdominal/thoracic surgery
2. Abnormal position e.g., prone
3. Patients with the risk of aspiration
4. Anesthetic technique involving artificial ventilation, cardiac arrest, respiratory arrest

Choice of Endotracheal Anesthesia

The choice of endotracheal anesthesia depends on:

1. Nature of surgery
2. Patient factors
3. Anesthetic factors

Technique of Endotracheal Intubation

1. Keep the head upon a headrest (about 10cm high), supine.
2. Extension of the head and flexion of the neck help alignment of the oral axis, pharyngeal, and the laryngeal axis into line, facilitating optimum visualization of the vocal cords.
3. Open the mouth with your fingers.
4. Introduce the laryngoscope in your left hand blade down along the right margin of the tongue. The tongue is then displaced to the left by rotating the blade.
5. Advance the curved blade in the midline to the glossoepiglottic fold (Vallecula).
6. Place the tip of the curved blade in the vallecula.
7. Expose the glottis by displacing the tongue and epiglottis anteroinferiorly to expose the vocal cords.
8. Better view the glottis by applying backward, upward, and rightward pressure on the thyroid cartilage (BURP). A good assistant is always helpful.
9. Introduce the tube from the right side of the patient's mouth with your right hand.
10. Attach the end-tidal carbon dioxide to the end of the endotracheal tube to confirm the correct placement of the tube. Also, assess for bilateral symmetrical breath sounds in the chest by auscultating the chest along the mid-axillary line with a stethoscope.
11. The endotracheal tube should be well-secured.

Disadvantages of Endotracheal Intubation

1. Needs adequate knowledge of anatomy and physiology
2. Requires experience and skill
3. Performed in a deeper plane of anesthesia
4. Hazards of endotracheal intubation, e.g., sore throat, laryngitis
5. Requires heavy and costly machines and equipment
6. Unconscious patient needs constant monitoring and special care

Securing & Maintenance – Airway Devices:

1. Artificial airway
2. Supraglottic airway devices
3. Tracheal tube

Airway Assessment

• Cervical spine movement
• T-M joint movement
• Mouth opening
• Modified Mallampati grading
• Thyromental distance

Artificial Airway

Purpose of an airway – lift the tongue and epiglottis away from the posterior pharyngeal wall.

Advantages of an airway:

• Cervical spine movement does not occur when the airway is inserted.
• Decreased work of breathing during spontaneous respiration using a face mask.

Types of Artificial Airway:

1. Oropharyngeal airway
2. Nasopharyngeal airway

OROPHARYNGEAL AIRWAY

Guedel airway:

• Parts – flange, bite portion, air channel

Uses:

1. To maintain an open airway
2. Prevent endotracheal tube occlusion
3. Prevent tongue bite
4. Facilitate suction
5. Conduit for passing devices into the oropharynx
6. Obtain a better mask fit

Contraindications:

1. Intact gag reflex
2. Oropharyngeal growth

Pre-requisites for Insertion

Size estimation

Methods of Insertion

Disadvantages

1. Due to incorrect size
2. Laryngospasm in an awake patient

Advantages:

1. Simple to use, cheap
2. Not associated with a sore throat
3. Does not cause bacteremia

NASOPHARYNGEAL AIRWAY

Parts:

• Flange
• Airway channel
• Bevel

Size:

• Inside diameter in millimeters

Size Determination:

• Method of insertion

Contraindications:

1. Anticoagulation
2. Basilar skull fracture
3. Nasal pathology, sepsis, or deformity of the nose or nasopharynx
4. History of epistaxis requiring medical treatment

SUPRAGLOTTIC AIRWAY DEVICES

Supraglottic devices fill a niche between the face mask and tracheal tube in terms of both anatomical position and the degree of invasiveness. These devices sit outside the trachea but provide a hands-free means of achieving a gas-tight airway.

1. Laryngeal Mask Airway Family
• LMA Classic
• LMA Unique
• LMA Flexible
• LMA Fastrach
• LMA CTrach
• LMA Proseal
2. Other Supraglottic Airways Similar to Laryngeal Mask
• Soft seal laryngeal mask
• Ambu laryngeal mask
• Intubating laryngeal airway
3. Other Supraglottic Airway Devices
• Laryngeal tube airway
• Perilaryngeal airway
• Streamlined pharynx airway liner

Laryngeal Mask Airway Family

LMA-Classic (standard LMA, Classic LMA, LMA-C, cLMA)

Parts:

1. Curved tube (shaft)
2. Elliptical spoon-shaped mask
3. Two flexible vertical bars
4. An inflatable cuff
5. An inflation tube
6. Self-sealing pilot balloon
7. 15-mm connector

cLMA size	Patient size
1	Neonates/infants up to 5 kg
1.5	Infants between 5 and 10 kg
2	Infants/children between 10 and 20 kg
2.5	Children between 20 and 30 kg
3	Children 30 to 50 kg
4	Adults 50 to 70 kg
5	Adults 70 to 100 kg
6	Adults over 100 kg

LMA-Unique

Disposable laryngeal mask airway (DLMA)

• Made of polyvinylchloride
• Identical dimensions to the standard LMA
• Stiffer tube and less compliant cuff
• Sizes available
• Suitable for out-of-hospital or ward use
• Insertion and placement similar to LMA-Classic
• Less increase in intracuff pressure with nitrous oxide

LMA-Flexible

Wire-reinforced, reinforced LMA (RLMA, FLMA, flexible LMA)

• Flexible, wire-reinforced tube
• Longer and narrower tube
• Not available in sizes 1 and 1.5
• Useful for head and neck surgeries
• Insertion method
• Disadvantages:
• Obstruction from biting
• Spiral reinforcing wire may become disrupted
• Only small tracheal tubes or bronchoscopes can pass through
• Not preferred for prolonged spontaneous ventilation
• Unsuitable for MRI scanning
• Malposition less easily diagnosed

LMA-FASTRACH

The LMA-Fastrach (intubating LMA, ILMA, ILM, intubating laryngeal mask airway) – designed for tracheal intubation.

• Parts –
  1. A short, curved stainless steel shaft with a standard 15-mm connector.
  2. Single, movable epiglottic elevator bar
  3. A V-shaped guiding ramp built into the floor of the mask.

LMA-FASTRACH Insertion Technique and Uses

• To facilitate tracheal intubation
• It can also be used as a primary airway device.

Tracheal Intubation using LMA Fastrach

1. Blind
2. Blind nasal
3. Fiberscopic guided
4. Light guided

Disadvantages

1. Pharyngeal pathology or limited mouth opening may make intubation difficult.
2. Cannot be used for intubation in patients below 30 kg.
3. The LMA-Fastrach tracheal tube is expensive & prolonged use is to be avoided.
4. The tracheal tube may be displaced downward or dislodged.
5. It should not be used in the prone position.
6. Unsuitable for use in the MRI unit.
7. Increased incidence of sore throat and difficulty swallowing.
8. In patients with immobilized cervical spine, exerts pressure on the cervical spine.

LMA-CTrach

• It has two built-in fiberoptic channels with a monitor.
• Sizes - 3, 4, and 5
• Insertion technique

Advantages

1. High first intubation attempt success rate with minimal neck movement.
2. Can be used during awake intubation in the presence of an unstable cervical spine.

Disadvantages

1. Poor image quality
2. The view may be obstructed by secretions, lubricant, or blood.
3. Cannot be used easily in the patient with a limited mouth opening.

LMA-ProSeal

• Parts - cuff, inflation line with pilot balloon, airway tube, and drain (gastric access) tube.
• Function of second dorsal cuff
• Insertion techniques – introducer, guided, digital methods
• Confirmation of proper placement

Uses

1. Can be used for both spontaneous and controlled ventilation.
2. Preferred in situations where higher airway pressures are required, better airway protection is desirable, and for surgical procedures in which intraoperative gastric drainage or decompression is needed.
3. Useful in cases where it is important to avoid airway trauma.
4. Safe for use in an MRI unit.

Disadvantages

1. The LMA-ProSeal is less suitable as an intubation device.
2. Higher resistance in spontaneously breathing patients than other devices.
3. Requires a greater depth of anesthesia for insertion.
4. Airway obstruction after insertion.
5. Gastric insufflation.
6. The LMA-ProSeal has a shorter life span.

LARYNGEAL TUBE AIRWAY

• Parts –
  1. The airway tube is wide, curved, color-coded on the connector.
  2. Single lumen that is closed at the tip.
  3. Small (esophageal, distal) cuff near the blind distal tip.
  4. Large (oropharyngeal, pharyngeal) cuff near the middle of the tube.
  5. One inflation tube to inflate both light blue cuffs.
  6. Two anterior-facing, oval-shaped openings (ventilation holes).
  7. Side holes lateral to the top of the distal opening.
  8. A ramp leads from the posterior wall toward the main ventilatory outlet.

• Reusable silicone or single-use versions made of polyvinylchloride.
• Insertion technique

Advantages

1. The LT is relatively easy to insert.
2. It is well tolerated during emergence.
3. Because the distal cuff fits over the esophageal inlet, the risk of gastric inflation is low.
4. Can be used with both spontaneous and controlled ventilation.
5. High ventilation pressures can be used.
6. This device may be especially useful for resuscitation (“cannot intubate, cannot ventilate” situation, obstetrics after failed intubation, edentulous patients).
7. The incidence of complications such as sore throat, mouth pain, or dysphagia is low.
8. Regurgitated liquid is less likely to be aspirated with the LT.

Disadvantage

1. Failure to ventilate if the tube enters the trachea – contrast combitube.

ENDOTRACHEAL TUBES

The Tracheal Tube (Endotracheal Tube, Intratracheal Tube, Tracheal Catheter)

The tracheal tube is a device that is inserted through the larynx into the trachea to convey gases and vapors to and from the lungs.

Parts

1. The machine (proximal) end
2. The patient (tracheal or distal) end
3. Bevel
4. Murphy eye
5. A radiopaque marker
6. Cuff Systems - consists of the cuff plus an inflation system, which includes an inflation tube, a pilot balloon, and an inflation valve.

Tube Type	Latex coated red rubber tubes	PVC tubes
Characteristics	Harden and become sticky with age, poor resistance to kinking, become clogged by dried secretions	Less likely to kink than rubber tubes. They are stiff enough for intubation at room temperature but soften at body temperature, so they tend to conform to the patient's upper airway.
Reuse	Reused multiple times	Disposable
Material	Latex	PVC
Transparency	Not transparent	Transparent
Kinking Resistance	Poor resistance to kinking	Less likely to kink than rubber tubes
Latex Allergy	Latex allergy in susceptible patients	No latex allergy

Oral Intubation

1. Direct Laryngoscopy
2. Blind Oral Intubation
3. Digital Technique
4. Fiberoptic Guided
5. Retrograde Intubation

Nasal Intubation

1. Direct Laryngoscopy
2. Flexible Fiberoptic Laryngoscopy
3. Blind Nasal Intubation

COMBITUBE

Device for difficult airway

Parts

1. Two separate lumens (pharyngeal & tracheoesophageal) that are fused longitudinally
2. Two inflatable cuffs.
3. Each lumen is linked by a short tube to a standard 15-mm connector at the breathing system end.
4. Pharyngeal lumen - occluded distal end and eight oval-shaped perforations (ventilating eyes) between the cuffs, colored blue.
5. Tracheoesophageal lumen - patent distal end and a clear tube.
6. The smaller distal cuff serves to seal either the esophagus or trachea, depending on its placement.
7. The larger (pharyngeal) cuff (balloon) is above the perforations.
8. The pilot balloon for the pharyngeal cuff is colored blue.

Sizes:

1. Regular (41 [Fr])
2. SA (37 Fr)

Recommended for patients with a height greater than 5 feet (152 cm).

Not recommended for patients younger than 12 years of age.

Method of Insertion

Indications

1. Airway management in the difficult-to-intubate patient
2. Massive airway bleeding or regurgitation.
3. Limited access to the airway and limited mouth opening
4. Cervical spine injury.
5. Useful in entertainers in whom it is important to avoid vocal cord damage.
6. In cardiopulmonary resuscitation in both prehospital and inhospital settings.
7. “Cannot ventilate, cannot intubate” situation.
8. Can be used during percutaneous dilatational tracheostomy or tracheotomy.

Contraindications

1. Active pharyngeal or laryngeal reflexes
2. Oesophageal trauma or pathology
3. Ingestion of corrosive agents
4. Oropharyngeal, pharyngeal, or hypopharyngeal mass.

Advantages

1. Time needed for insertion is short and less skill is required
2. Can be inserted in the presence of blood or secretions in the oropharynx.
3. Provides comparable ventilation and improved oxygenation to that of tracheal intubation
4. It can be used by an anesthesia provider having limited use of the left arm.
5. It is well tolerated by the patient during emergence from anesthesia.
6. Its use is not associated with high levels of trace gases.
7. Decreased risk of accidental extubation.
8. The Combitube provides good but not complete protection from aspiration.

Disadvantages

1. Tracheal suctioning or fiberoptic bronchoscopy is not possible through the Combitube in the esophageal position
2. High airflow resistance
3. Insertion and removal of the Combitube is associated with a higher stress response
4. Trauma to the airway and esophagus
5. Sore throat and dysphagia
6. Unsuitable for use in a patient with latex allergy
7. The Combitube is expensive compared to other single-use devices